Due
to its physical properties, petroleum (parafin) burns in a different way.
This has to be respected to find an appropriate way to use Jatropha oil
for lighting.

The two pictures below show the
principle difference of the burning process. The pictures
further below explain this proces in detail.

burning
Petroleum

burning
Jatropha oil

By the capillary effect the
petroleum moves some cm upward in the wick. When lit, the flame
heats up the petroleum. It evaporates and the vapor burns. The wick
itself does not burn, it is only the transport device for the petroleum.

Due to its higher viscosity
the capillary effect is smaller and the plant oil cannot be transported
as high as the petroleum. Since it does not evaporate, it burns
directly on the surface of the wick. The heat of the flame causes
cracking of the oil molecules, so a deposit of carbon is developed.
This has to be removed from time to time.

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The wick is
placed into the oil.

The oil mounts
in the wick by capillary forces. But much less higher than petroleum.

So the wick
has to be short.

The flame should
be near the surface of the oil to make sure that enough oil to be
burnt is transported.

The oil burns
at the surface of the wick. The wick itself burns too.

The high temperature
of the flame causes some oil molecules to break. Carbon deposits
are formed on the wick. After some time the capillarity forces are
too small to transport the oil through the carbon deposit.

The carbon
deposit has to be removed.

The wick is
pulled up to replace the burnt material.

This priciples
are respected in the design of this "Binga lamp".

The floting
disc, wrapped with aluminium paper, holds the wick in the centre
and makes sure that the flame is only some mm above the surface
of the oil.

This lamp works
for up to 8 hours without interruption. Afterwards the visible part
of the wick is completely carbonised and has to be replaced.